If you (or someone sending a book to you) send with PBS DC, you can click the green check mark on the Books I've Mailed or En Route to Me tabs and it shows a map of the US and where PBS estimates the book is in its travels. If there is a DC scan, the truck will go to where the scan was and start moving from there, so sometimes it seems to "go back" across the country. The scans in the Details are more accurate, obviously.

Yes, it is a fun feature for entertainment only and the time and route is an estimate - except that the route will reflect actual scans from USPS along the way. If you click on the truck image it will audibly honk its horn. It is NOT an accurate record of the USPS journey your book is taking.